1. Field of the Invention
This invention relates to a new diaphragm pump which by preventing the diaphragm undergoing deleterious abnormal deformation or puckering allows effective, long-lasting and reliable pumping of fluids with any gas content.
2. Description of the Related Art Including Information Disclosed Under 37 C.F.R. .sctn..sctn.1.97-1.99
From the state of the art and more precisely from the preceding European Patent No. 0250026 of Apr. 1, 1992 of the present applicant, a device is already known for specifically pumping fluids of high gas content by means of diaphragm pumps, i.e. pumps in which an elastomeric diaphragm separates the fluid to be handled from the hydraulic operating oil. For this purpose said known pumps use substantially hemispherical internal elastic diaphragms having a thickness which decreases from their edge, fixed to the centre plane through the pump casing, to their centre, and are reinforced by embedded fabric and a series of metal rings arranged concentrically parallel to the plane on which the diaphragm is fixed to the pump casing, said rings of the series having a cross-section which decreases from the edge towards the centre of the diaphragm. Experience has shown that this known type of diaphragm pump has a series of drawbacks, of which the most important is related to the arising of abnormal deformation in a critical region of the diaphragm located in proximity to its connection to the pump casing, where failure occurs due to fatigue. In substance, it has been found that following the varying shape assumed by the diaphragm during pump operation, deformation occurs in said critical diaphragm region in the form of wrinkles which travel along said region to cause fatigue failure triggered by small defects which are always present and are difficult to eliminate, even with very careful manufacturing processes. A further drawback of said known diaphragm pump is that the elastic diaphragm presses directly against the holes provided for housing the intake and delivery valves for the fluid to be pumped, the edges of these holes then inevitably fracturing, as has been found in practice.